Let 
be the 20 marks of the boys, and 
be the 10 marks of the girls.
We know that the global mean was 70, meaning that
Multiplying both sides by 30 we deduce that the sum of the scores of the whole classroom is
By the same logic, we work with the marks of the boys alone: we know the average:
And we deduce the sum of the marks for the boys:
Which implies that the sum of the marks of the girls is 
And finally, the mean for the girls alone is
Y = $35.25(6) + 40
y = $211.5 + $40= $251.50
the answer is a
Answer:
Step-by-step explanation:
A circle is inscribed in an equilateral triangle PQR with centre O. If angle OQR = 30°, what is the perimeter of the triangle?
This is a circle inscribed in an equilateral triangle with side s.
If you are asking for the perimeter of PQR, it is 3s.
If you are asking for the perimeter of OQR, it is (3+23–√3)s
Since OR and SR are the hypotenuses of right triangles with adjacent side equal to ½ s, their length is ½s / cos 30° = (√3) /3.
(3/3)s + ((√3) /3)s + ((√3) /3)s = ((3 + 2√3)/3)s ≈ 2.1547s
Hope it helps
help me by marking as brainliest....
Simple interest = Cost Price + (Interest Percentage of Cost Price × number of years or months we are paying off)
a) SI = £20 000 + (5% of £20 000 × 4)
SI = £20 000 + (£1000 × 4)
SI = £20 000 + £4000 = £24 000
b) SI = £20 000 + (5% of £20 000 × 3)
SI = £20 000 + (£1000 × 3)
SI = £20 000 + £3000 = £23 000
£24 000 - £23 000 = £1000 that you saved!
Remark
You must use the sin law to find this.
Multiply through by 12
12 * *12
0.5269 = sin(x)
Now you have to use the inverse of the sine function.
Use your calculator for that
2nd F
sin-1
(0.5269)
= 31.79 degrees. <<<<<< Answer.
There sometimes is a second answer. I don't think there is in this case.
